I am considering to write some rewrite rules in a .htaccess file that meets the following conditions:
when user requests an url like : http://localhost/img.php?w=12&h=21&d=5
apache would check whether the file named "images/img_12_21_5.jpg" exists, if yes, just rediect to the file; however if no, the browser will redirect to a file named "images/blank.gif";
Can it be implemented just using apache rewrite rules? Thank you.